Pilot Voided Volume Validation Study: Sound-Based Smartphone Applications Can Accurately Measure Voided Volume

Abstract

Background/Objectives: The objective of this study was to test the accuracy of two sound-based voided volume measurement applications compared to voided volume based on the measurement of pre- and post-void weight using a high-resolution scale. Methods: Seven male and four female volunteers participated. Male and female volunteers used the proudP and Healthy Bladder-Voiding Diary mobile apps, respectively, to measure sound-based voided volume (SVV). The difference between pre- and post-void weight was calculated and converted to mL to be the true voided volume (TVV) using a high-resolution scale. Pearson correlation coefficients were calculated, and paired t-tests were completed. Results: Eighty-one voids were recorded (42M/39F). The median male participant age was 25 years. Male SVV ranged from 42 to 790 mL, and TVV ranged from 61 to 880 mL. The mean difference was 39 mL (95% CI, 18–59 mL). SVV and TVV comparison revealed a strong correlation (r = 0.977, p < 0.0001). Bland–Altman analysis revealed a mean bias of 39 mL. The median female participant age was 25 years. Female SVV ranged from 32 to 440 mL, and TVV ranged from 20 to 682 mL. The mean difference was 55 mL (95% CI, 23–88 mL). SVV and TVV comparison revealed a correlation (r = 0.882, p < 0.0001). Bland–Altman analysis demonstrated a mean bias of 55 mL. Conclusions: In this pilot study, we found that the male and female apps have a strong correlation to true voided volume (male > female app) and can be used by patients to track voided volume at home. The male app accurately measures voided volume within 60 mL from the TVV; however, the female app is less accurate. These preliminary findings warrant validation in larger prospective cohorts.